Reliability of Small Biopsy Samples Compared With Resected Specimens for the Determination of Programmed Death-Ligand 1 Expression in Non-Small-Cell Lung Cancer

Expression of programmed death-ligand 1 (PD-L1) in nonesmall-cell lung cancer (NSCLC) has mainly been examined using surgically resected specimens. We retrospectively evaluated the expression of PD-L1 using immunohistochemistry in 79 paired small biopsy and resected specimens of NSCLC. The concordance between the samples was good, with a concordance rate of 92.4% and k value of 0.8366. Background: Several studies have assessed the expression of programmed death-ligand 1 (PD-L1) in resected surgical specimens of non-small-cell lung cancer (NSCLC). However, the expression of PD-L1 in smaller biopsy samples of advanced NSCLC has not been reported. Patients and Methods: A total of 79 patients with NSCLC at our institution with available biopsy samples and resected specimens were retrospectively enrolled in the present study. PD-L1 expression was assessed by immunohistochemistry and scored using the hybrid scoring method. The concordance rates for the expression of PD-L1 between the 2 samples were analyzed. Results: The pathologic stage of the patients (51 men, 28 women; median age, 68 years) was stage I in 37, stage II in 18, and stage III in 24. The diagnostic procedures included transbronchial biopsy in 59, transbronchial needle aspiration biopsy in 14, and computed tomography (CT)-guided needle biopsy in 6. The positivity rate of PD-L1 in these samples was 38.0% (27 transbronchial biopsies, 6 transbronchial needle aspiration biopsies, 3 CT-guided needle biopsies) versus 35.4% in the resected specimens. The median hybrid score was 0 (range, 0-170), and the mean score was 28.7 +/- 43.4. Comparing the biopsy samples and resected specimens with a score of >= 1 as positive for PD-L1 staining, 6 tumors were discordant for PD-L1 expression and 73 were concordant, for a concordance rate of 92.4% and kappa value of 0.8366. Conclusion: PD-L1 status showed good concordance between the biopsy samples and resected specimens. These small samples, even those derived from transbronchial needle aspiration biopsies, appear adequate for the assessment of PD-L1 expression. (C) 2015 Elsevier Inc. All rights reserved.